1. Field of the Invention
The present invention relates to serum-based vaccines that are substantially free of non-host albumin and processes for preparing and using the same. More specifically, the present invention relates to the inventive concept of vaccines that prevent or substantially reduce post-vaccination adverse systemic reactions associated with adjuvanted vaccine regimens.
2. Brief Description of the Prior Art
It is known in the art that vaccination of animals with vaccine regimens involving the use of adjuvants can cause adverse systemic reactions. The vaccine regimen can comprise administration of inactivated vaccine containing an adjuvant. Alternately, the vaccine regimen can comprise administration of a modified live vaccine and an inactivated vaccine containing an adjuvant. Illustratively, most feline vaccine regimens comprise administration of a vaccine containing a modified live organism concomitantly with a vaccine containing an inactivated organism and an adjuvant. Associated with these vaccination regimens are adverse systemic post vaccination reactions. For instance, the use of feline leukemia vaccines (FeLV) can cause post-vaccination reactions including excess salivation, vomiting and diarrhea. See the monograph on FEL-O-VAX Lv-K vaccine in the Compendium of Veterinary Products, page 486, Third Edition, 1995-1996. The adverse systemic reactions include anaphylaxis, hypersensitivity and atypical reactions such as vomiting and diarrhea.
Contrary to the present inventive concept, the prior art has attributed the above named systemic reactions to the presence of adjuvants, endotoxins, cellular debris residue, high concentration of modified live viruses or high antigenic mass. Dodds, Vaccine Safety and Efficacy Revisited: Autoimmune and Allergic Diseases on the Rise, Vet. Forum, pp 68-71, May, 1993 noted an increase in post-vaccination autoimmune and allergic diseases. Dodds has postulated that the increase is due to the immunological burden on susceptible animals exposed to a combination vaccine containing modified live organisms and adjuvanted, killed bacterins administered at the same time (as the diluent). Dodds also postulated that the immunological burden is produced by the effect of the modified live organisms.
The search for safe and effective vaccines has been limited by the paucity of information regarding the source of the problem of post-vaccination reactions. There is no indication in the literature or otherwise that teaches that these systemic reactions could be caused by an interaction of non-host albumin with an adjuvant. Indicating the contrary is the prevalent use of non-host albumin in the presence of adjuvants. Dogs receive adjuvanted rabies vaccine at the same time that they receive modified live combination vaccines containing non-host albumin. Cats receive adjuvanted FeLV vaccine in a vaccine regimen comprising the concomitant administration of a modified live vaccine containing non-host albumin. Also, combinations of albumin and adjuvants are commonly used in the art to evaluate the effectiveness of adjuvants. Albumin, generally in the form of Bovine Serum Albumin (BSA), is formulated with various adjuvants and each formulation is injected into non-bovine animals. The animals are bled at some later date and their sera are measured for antibody responses to BSA. The animals showing the best antibody responses are considered to have received the most effective adjuvants. Prince et al, U.S. Pat. No. 4,164,565 discloses the use of non-host albumin as a stabilizer in vaccines. Wiedmeier et al., Pediatric Research, Vol.3, page 262-267, September, 1987 discloses reactivity in mice produced by immunization with Bordetella pertussis combined with Bovine albumin. Notably, Wiedmeier et al teaches that the cause of reactivity is the pertussis toxin in combination with albumin.
To help reduce the systemic reactions, one can purify vaccines to remove components thereof which presumably cause the systemic reactions. Animal vaccine preparations are typically purified by conventional methods such as filtration, diafiltration or centrifugation to remove components such as cells and cellular debris. Other methods of purification that yield highly purified antigens are seldom employed because they are cost prohibitive in the preparation of animal vaccines. Illustrative of the other methods of purification is column chromatography, including ion exchange chromatography, molecular sieve chromatography and hydrophobic interaction chromatography. Moreover, highly purified antigens are difficult to adjuvant with the commonly used adjuvants because they are not effective enough to stimulate a protective response with purified antigens. At any rate, these purification methods were not effective for removing non-host albumin from vaccines or precursors thereof.
The art has not attributed the cause of systemic reactions to the presence of adjuvants and non-host albumin. Certainly, the art has not attributed the cause of systemic reactions to the presence of non-host albumin in the vaccine regimen involving the use of adjuvants.
By the present invention, it has been realized that the presence of non-host albumin in an adjuvanted vaccine or vaccine regimen can cause systemic reactions. By the present invention, there is provided a novel serum-based adjuvanted vaccine or vaccine regimen that is substantially free of non-host albumin and a method of preparing the same.
In accordance with the foregoing, the present invention encompasses a serum-based vaccine comprising an immunogenically effective amount of an antigen and an adjuvant wherein said vaccine is substantially free of non-host albumin. The term xe2x80x9cserum-basedxe2x80x9d is used herein to denote that the vaccines of the invention or their precursors employ serum including non-host serum. Typically, the serum is employed in growth media to enhance growth of organisms that are employed in the preparation of the vaccine. By the term xe2x80x9cprecursor of the vaccinexe2x80x9d is meant vaccine components, particularly antigen, proteins other than antigen, whole organisms and harvest material. By the term xe2x80x9cimmunogenically effective amountxe2x80x9d is meant that the antigen contains a protective component in a concentration that is sufficient to protect animals from a target disease when an adjuvanted vaccine containing the antigen is administered to animals. By the term xe2x80x9cantigenxe2x80x9d is meant a biological material (natural, recombinant or synthetic) that stimulates a protective immune response in animals. By the term xe2x80x9cadjuvanted vaccinexe2x80x9d is meant a vaccine containing an adjuvant, or a plurality of vaccines administered as a part of a vaccine regimen wherein at least one of the vaccines contains an adjuvant. By the term non-host albumin is meant albumin from the serum of an animal species other than the animal species being vaccinated. Albumin is a simple protein found in serum and has a molecular weight of about 66,000 daltons. A vaccine which is substantially free of non-host albumin contains less than 1.0 mg/mL of non-host albumin.
Also encompassed by the invention is a method of preparing the serum-based vaccine that is substantially free of non-host albumin comprising removing non-host albumin from the vaccine or a precursor thereof. An alternate method of preparing the serum-based vaccine that is substantially free of non-host albumin comprises providing a host serum containing host albumin in the preparation of the vaccine.
Further encompassed by the invention is a vaccine which is prepared by adding host serum or albumin to the vaccine antigen after harvesting or purifying the antigen from a culture of an organism from which the antigen is derived, but prior to adjuvanting the antigen. Additionally, the host serum or albumin can be added to the antigen after harvesting but prior to lyophilizing the antigen if the antigen is a modified live organism. When host serum or host albumin is used in this manner, it acts as a stabilizer. The term xe2x80x9cstabilizerxe2x80x9d means any additive that is added to a vaccine to prevent degradation of the antigen and the consequential loss of immunogenicity of the vaccine.
In a presently preferred embodiment of the invention, the method of preparing a serum-based vaccine containing an immunogenically effective amount of an antigen and an adjuvant wherein said vaccine is substantially free of non-host albumin comprises:
(a) growing an organism which produces the antigen in a culture containing non-host albumin;
(b) harvesting the culture;
(c) clarifying the harvest;
(d) separating the antigen and non-host albumin from the clarified harvest;
(e) separating the non-host albumin from the antigen;
(f) collecting the antigen; and
(g) formulating the antigen with an adjuvant.
In an additional preferred embodiment of the invention, the method of preparing a serum-based vaccine containing an immunogenically effective amount of an antigen and an adjuvant wherein said vaccine is substantially free of non-host albumin comprises:
(a) growing an organism which produces the antigen in a culture containing non-host albumin;
(b) harvesting the culture;
(c) clarifying the harvest;
(d) separating the antigen from the non-host albumin by passing the clarified harvest through a column with a matrix which selectively binds the antigen;
(e) washing the column matrix to remove excess non-host albumin;
(f) discarding the wash solution;
(g) washing the column matrix with a solution which elutes the antigen from the column matrix;
(h) collecting the antigen; and
(i) formulating the antigen with an adjuvant.
In another preferred embodiment of the invention, the method of preparing a serum-based vaccine containing an immunogenically effective amount of an antigen and an adjuvant wherein said vaccine is substantially free of non-host albumin comprises:
(a) growing an organism which produces the antigen in a culture containing non-host albumin;
(b) harvesting the culture;
(c) clarifying the harvest;
(d) separating the antigen from the non-host albumin by passing the clarified harvest through a column with a matrix which selectively binds the non-host albumin;
(e) collecting the antigen; and
(f) formulating the antigen with an adjuvant.
In still another preferred embodiment of the invention, the method of preparation of a serum-based vaccine containing an immunogenically effective amount of an antigen and an adjuvant wherein said vaccine is substantially free of non-host albumin comprises:
(a) growing an organism which produces the antigen in a culture containing host albumin;
(b) harvesting the culture;
(c) clarifying the harvest, if necessary; and
(d) formulating the harvest with an adjuvant.
Further encompassed by the invention is a method of eliminating adverse vaccine reactions in animals comprising administering to said animals a vaccine regimen which is substantially free of non-host albumin.
The method for eliminating adverse reactions in animals comprises administering to said animals an adjuvanted vaccine or an adjuvanted vaccine regimen which is substantially free of non-host albumin.
Also encompassed by the invention is a process for stabilizing an antigen comprising adding host serum or host albumin to said antigen prior to adjuvanting the antigen. Such a process for stabilizing an antigen can also comprise adding host serum or host albumin to said antigen prior to lyophilizing the antigen.
The vaccines of the invention are applicable for use in preventing or treating diseases of all species of animals. They are particularly suitable for use in preventing or treating diseases of companion animals such as cats, dogs and horses which are particularly sensitive to adjuvanted vaccine regimens comprising non-host albumin. In particular, the vaccines of the invention are suitable for use in preventing feline leukemia (FeLV) and rabies because they are free of problems that typically attend such vaccines FeLV vaccines are notorious for causing adverse reactions such as hypersalivation, vomiting, diarrhea and sometimes death. Often, these reactions occur within minutes of administration of the vaccine.
Surprisingly, it has been found that animals to which the vaccines of the invention have been administered have virtually no adverse systemic reactions. The discovery that non-host albumin in a vaccine containing an adjuvant or administered in a vaccine regimen with a vaccine containing an adjuvant can cause systemic reactions is thus a part of the invention. This and other aspects of the invention are described more fully hereunder.